Posted
by
kdawson
on Friday June 04, 2010 @09:38AM
from the mere-pimple dept.

Omomyid and other readers send in the news that the bright flash of an impact on Jupiter has been observed — and caught on film — by amateur astronomers. That WMV is from amateur Christopher Go. Here's Anthony Wesley's video (45 MB AVI; the site is already overloaded). In the larger video you can see the impact lasting for a couple of seconds, and a good deal of structure is visible. The amateurs report that no dark debris field developed around the impact site in the time before it rotated out of sight; this may indicate that the impactor burned up high in Jupiter's atmosphere. Soon professional astronomers, and possibly Hubble, will be on the job.

It won't. A gas giant is a star that never happened. There' no do-over whereby a gas giant might become a star subsequently.

Not for Jupiter, but it likely happens all the time in the rest of the galaxy.

From what I remember, fusion occurs somewhere from 15-75 Jupiter-Masses (Mj). If you had a gas giant with 95% of that mass it could consume the remainder necessary for its gravity to become strong enough to start a continuous fusion reaction. Fusion likely does occur with smaller objects, but not on stellar scales/timelines and likely with deuterium instead of just Hydrogen (which fuses more near the 75 Mj mark).

Interestingly, a star that is just large enough to begin fusing hydrogen will look smaller than Jupiter due to the increased gravity pulling all the gas in.

The mechanic should occur, since it is the same mechanic we observe for a type of supernova in which a near-supernova capable sized white-dwarf pulls matter from a smaller partner in a binary system.

I wouldn't be surprised if you had near-brown dwarf sized gas giants tripping the limit by pulling in extra matter (even other gas giants)